Aston Martin has been offered a new site and financial incentives to build its new generation DBX crossover in Macedonia and not Wales or another UK site.
The eastern European state had previously made a bid to win the investment but was not shortlisted and has now made a renewed offer with greater financial incentives and AM is said to be reconsidering the country.
The new offer will come as a shock to Wales, which has been working to secure the investment at St Athan, near Cardiff and backed by PM David Cameron.
Another site close to the Aston Martin plant in the Midlands was in the running but is now thought to have been ruled out.
AM began with a list of 19 possible locations several months ago then narrowed the list down to two UK sites, one in the U.S. state of Alabama and a Middle Eastern location, said Reuters last month.
But in the last few weeks the former Yugoslav republic has made an improved offer to the carmaker, which has previously said that any potential financial support is an important factor in making its choice, according to the sources.
Macedonia has been working to attract the automotive components supply industry to feed European vehicle assembly plants.
This late bid by Macedonia is likely to further delay an announcement about the DBX production centre which was expected this month.